Hello everyone,
First post here, after scouring for helpful tips that have helped me get this far. Figured I would register to ask this community since there seems to be a lot of knowledgeable folks here!

Truck is a 1991 F-150, 4.9 liter, inline 6, automatic. Fires right up, but once it hits around 35 mph it began missing(felt like it was running out of gas), and shifting into 2nd and 3rd was rough and sudden.

Pulled the codes and found the O2, TPS, ICM, EGR, IAC valve, and SPOUT Connectors were the culprits.

Replaced all of them, including the EGR positioning sensor, and the EGR Vacuum Solenoid. Also found a few vacuum lines that needed some repair, and corrected them too. Fuel filter and pump relay were also replaced, and distributor(entire assembly), along with wires and plugs. Engine was also retimed at 10 BTDC as noted under the hood, and the SPOUT was pulled prior to the timing being completed.

The engine is still missing though, and the only code that keeps coming up is 213. When I unplug the spout, it runs great. I have checked the continuity between the two female plugs on the spout and was getting around 6.5ish--had the reader set to 20k ohms. How do I check if there is a short somewhere between the spout and the wiring? I am a little overwhelmed at the size of the looms and am not sure which wire is the correct one to tap into. I am more of a visual learner, so if anyone could simplify how to test for a short or a bad ground I would be more than appreciative.

 

Which automatic does it have? Put all the truck's details into your signature so we can review them with each reply, as this caption explains:


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Codes do not identify culprits - they only indicate what circuit is out-of-spec, which is where YOU have to begin your diagnosis. When you find codes, post each code number & each COMPLETE definition. You should NOT blindly replace parts whose names are mentioned in the definitions. This caption contains the Ford definitions specific to these trucks:


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If you kept the original parts (which are usually better than any replacements), I recommend you put them back on.

What did the old spark plugs look like?


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What is the fuel pressure?


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If you don't have a Haynes manual, follow the link in this caption:


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When you have one, read the diagnostic procedure in Ch.5 (usually Sec.5 or 7, depending on edition).

 

Thank you Steve83!!

Trans is E

I have not just blindly replaced parts, but instead went by feel, and then searched codes to see if symptoms lined up.

This is the list of codes in the past, that have since cleared after replacement. Symptoms have also disappeared after replacement.121
(O,R,M)
Throttle Position (TP) sensor out of range – TPS
126
(O,R,M)
MAP or BARO sensor out of range – “>MAP
128
(M)
MAP vacuum has not been changing – check vacuum lines – “>MAP
191
(M)
Fuel system was rich at idle – Left or Front HO2S – Fuel control
213
(R)
Ignition SPOUT or SAW circuit open or shorted – Ignition Systems
334
(O,R,M)
EVP sensor is/was high – EVR
556
(O,M)
Fuel pump relay primary circuit fault – Power / Fuel Pump Circuits

Code 213 is no longer surfacing. I reset the timing to 0, warmed up the engine, pulled the SPOUT, and set to 10 BTDC--also double-checked and confirmed the firing order is proper.

The engine is still sputtering though. I rechecked the codes and 334 is the only one surfacing now. I have purchased a Motorcraft Valve Positioning Sensor to no avail. I pulled and plugged the vacuum line and the engine ran great. I also put my finger over the vacuum line at idle and felt suction. So if my research has led me down the correct path that means there is a circuit issue with the EGR valve?

 

Spark plugs were not in good shape. #6 was smashed as noted in the photo. The other 5 were appropriately gapped but were in need of replacement.

 

I love a good mystery and you have provided all of the clues to help solve yours. I believe you still have a vacuum leak. There is a small white hose near the blower motor that likes to decay and fall apart.

The EGR requires a lot of vacuum to function properly. When it's not working as it should you can get drivability problems like you describe. In addition the code is telling you the EGR position does not match what is commanded by the ECM. With vacuum removed from the EGR it stays closed and the truck runs fine.

 

sdmartin65!!!

Holy s*&!@%$#%&$(

Found it, and there was some small decay around the connection near the regulator on the top. Real small decay, looked like pinholes or smaller. So to be safe I cut it off and replaced it with some repair tubing I had.

Ran the engine, got it up to operating temperature and gave it a spin. No issues!! Pulled it back into the garage, shut it off, ran the codes and got the wonderful 111-Systems Pass OK

Thank you so much!!!